(click to enlarge)

I have been seeing these around my tank, above the waterline! They move and duplicate if cut in half. They do NOT have a triangle head. If they get in the water they are light pink and they squirm around.

There are not many around the tank. Just a couple above the waterline, and on the lid - that is, if I see them I get them out as soon as possible! Are they going to kill my fish? I have 6 flame tetras, 2 apple mystery snails and 2 bottom feeders.

Also, there’s a over growth of green algae, just splotches of green on the walls, I have a scrubber, but it keeps growing. Help me please!


It looks like some type of leech and there is about 500 types that live in water.

Some of them feed on the body fluid from snails and others feed on body fluids from fish or other animals that live in or come in contact with water.

It is impossible to identify it from your picture.

Another possibility is it might be a type of nemathode. Some can be parasites on fish while others live of bacteria and organic waste or on plants.

Nobody knows how many types of nemathodes there is on our planet but it is more than 2270 types on land and in water.

Sorry but it is not possible to identify it whithout a lot more information. For now I suggest you remove the ones you see and vacum the gravel every time you do the weekly water changes (to get rid of the ones living in the gravel/sand).

Some predatory fish will eat them so it is possible to get rid of the problem in a natural way.

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